JPH0718003Y2 - Magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is a magnetic card in which two terminals having opposite polarities are connected in parallel to both terminals of a magnetic core winding for signal input / output. Read magnetic head.

<Prior Art> A magnetic card coated with a magnetic recording medium and capable of writing or reading a signal with a magnetic head is often used. Conventionally, this type of magnetic card is generally easily forged, and its prevention is performed by a signal writing method or a change of a magnetic head.

<Problems to be solved by the invention> However, in order to prevent forgery of a conventional magnetic card, it is necessary to combine writing and reading methods, and it is difficult for the magnetic head to prevent complete forgery.

<Means for Solving the Problems> In the present invention, except for such drawbacks of the related art, the winding end lead of a magnetic head having a magnetic core having a winding serving as a signal input / output line butted with a magnetic gap This is a read-only magnetic head in which two diodes having opposite polarities are provided in parallel between lines or between signal input circuits.

<Operation> In the past, when the voltage induced in the winding is small, the diode has a large resistance value and the input and output terminals are almost open when a read operation is performed, but a signal is output, but a large voltage like a write operation When applied to the diode, the diode is limited to the forward voltage, or the diode is destroyed and writing is disabled.

<Embodiment> An embodiment of the magnetic head of the present invention is shown in a principle view of FIG. 1, an exploded perspective view of FIG. 2 and a vertical assembly side view of FIG.

As shown in the drawing, two diodes 3 having different polarities are provided between winding terminals 6 of a magnetic head having a magnetic gap 1 provided with a front end portion 4 of a magnetic core 1 provided with a winding 2, and a magnetic gap 5.
Connect 3'in parallel. These magnetic heads, together with the diodes 3 and 3 ', are assembled in a magnetic shield case 7 shown by a dotted line and filled with resin, and terminals 8 for connecting to an external circuit
8'is connected to the winding terminal 6 to form a read-only magnetic head. Also, as shown in FIGS. 2 and 3, the same 2
An embodiment in which the individual magnetic cores 1 are butted to form the magnetic gap 5 is also obtained.

When reading a signal from the magnetic card, the voltage induced across the winding 2 is usually several hundred millivolts. However, since the forward voltage of the diodes 3 and 3'is generally about 0.7 volt, the diode 3 which is forward to the output voltage of the two diodes 3 and 3'has a large resistance when the output voltage is sufficiently low. In addition, since the polarities are opposite to each other and are connected in parallel, the output circuit is in an open state and the output signal is directly output to the terminals 8 and 8 '.

However, on the contrary, when writing from terminals 8 and 8 ',
Even if a high write signal is applied to 8,8 ', the voltage between terminals 2 and 2'does not exceed 0.7 volt with respect to the positive and negative voltage.
If a higher voltage is applied, the diodes 3, 3'or part of the power supply circuit element will be destroyed. Therefore, by making the winding 2 such that the voltage to the winding 2 of the magnetic head cannot exceed 0.7 V, writing cannot be performed and forgery is prevented.

Even if one phase direction diode is connected without connecting the diodes 3 and 3'in the forward direction only in parallel in the opposite direction, the amplifier circuit input from the terminals 8 and 8 ' A resistor capacitor, zener diode, or transistor may be used for the.

<Effect of Device> As described above, according to the present invention, simply connecting the diodes 3 and 3 ′ to the input / output terminals of the magnetic head makes it impossible to write on a magnetic card, etc., and is effective in preventing forgery. is there.

[Brief description of drawings]

FIG. 1 is a principle view of an embodiment of a magnetic head of the present invention, FIG. 2 is an exploded perspective view according to an embodiment of the present invention, and FIG. 3 is a vertical sectional side view of the assembly of FIG. In addition, 1: magnetic core, 2: winding, 3, 3 ′: diode, 4: front end part, 5:
Magnetic gap, 6: winding terminal, 7: magnetic shield case, 8,
8 ': Terminal.

Claims (1)

[Scope of utility model registration request] 1. A diode (3) between two lead lines of a winding (2) in a magnetic head in which a magnetic core (1) provided with a winding (2) serving as a signal input / output line is abutted to form a magnetic gap (5). Read-only magnetic head with 3'connected with different polarities.